Lookup field is not a specific field type. We can look up any type of field from a linked base. The type of a lookup field is determined by the original field in the linked base and has the isLookup property. Lookup fields cannot be edited.
All field return values may have isMultipleCellValue: true in certain cases:
  1. This occurs when the field is a lookup field. When the linked value allows multiple selections, the lookup field value will necessarily be an array.
  2. Fields can be configured - for example, user fields and link fields can be configured as single or multiple selection. In your code, you can use field.isMultipleCellValue to determine if a field accepts multiple values.
Do not use field type to determine write permissions. Instead, use the isComputed property of the field.

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1. Number Field

  • type: number
  • Write type: number
  • Return type:
    • isMultipleCellValue: false: number
    • isMultipleCellValue: true: number[]
Example: 
// Write value
42

// Return value (isMultipleCellValue: false)
42

// Return value (isMultipleCellValue: true)
[42, 17, 99]

​
2. Single Line Text Field

  • type: singleLineText
  • Write type: string
  • Return type:
    • isMultipleCellValue: false: string
    • isMultipleCellValue: true: string[]
Example: 
// Write value
"Hello, Teable!"

// Return value (isMultipleCellValue: false)
"Hello, Teable!"

// Return value (isMultipleCellValue: true)
["Hello, Teable!", "Welcome", "Good day"]

​
3. Long Text Field

  • type: longText
  • Write type: string
  • Return type:
    • isMultipleCellValue: false: string
    • isMultipleCellValue: true: string[]
Example: 
// Write value
"This is a long text field that can contain multiple paragraphs..."

// Return value (isMultipleCellValue: false)
"This is a long text field that can contain multiple paragraphs..."

// Return value (isMultipleCellValue: true)
["This is a long text...", "Another long text...", "Yet another long text..."]

​
4. Single Select Field

  • type: singleSelect
  • Write type: string (option value)
  • Return type:
    • isMultipleCellValue: false: string
    • isMultipleCellValue: true: string[]
Example: 
// Write value
"Option A"

// Return value (isMultipleCellValue: false)
"Option A"

// Return value (isMultipleCellValue: true)
["Option A", "Option B", "Option C"]

​
5. Multiple Select Field

  • type: multipleSelect
  • Write type: string[] (array of option values)
  • Return type: string[]
Example: 
// Write value
["Red", "Blue", "Green"]

// Return value
["Red", "Blue", "Green"]
  • type: link
  • Write type:
    • isMultipleCellValue: false: { id: string }
    • isMultipleCellValue: true: { id: string }[]
  • Return type:
    • isMultipleCellValue: false: { id: string, title?: string }
    • isMultipleCellValue: true: { id: string, title?: string }[]
Example: 
// Write value (isMultipleCellValue: false)
{ id: "rec123456" }

// Write value (isMultipleCellValue: true)
[{ id: "rec123456" }, { id: "rec789012" }]

// Return value (isMultipleCellValue: false)
{ id: "rec123456", title: "Related Record 1" }

// Return value (isMultipleCellValue: true)
[
  { id: "rec123456", title: "Related Record 1" },
  { id: "rec789012", title: "Related Record 2" }
]

​
7. Formula Field

  • type: formula
  • Write type: Cannot be written directly
  • Return type: Depends on formula result, can be string | number | boolean or their array forms
Example: 
// Return value (isMultipleCellValue: false)
42 // or "Result" or true

// Return value (isMultipleCellValue: true)
[42, 17, 99] // or ["Result1", "Result2"] or [true, false, true]

​
8. Attachment Field

To upload an attachment to an attachment field, use the dedicated API. For details, see the Upload Attachment section.
  • type: attachment
  • Write type: 
    {
  id: string;
  name: string;
  path: string;
  token: string; // Unique identifier
  size: number; // File size in bytes
  mimetype: string; // File type
  presignedUrl?: string; // File preview/download URL
  width?: number; // Image width
  height?: number; // Image height
}[]
  • Return type: 
{
  id: string;
  name: string;
  path: string;
  token: string; // Unique identifier
  size: number; // File size in bytes
  mimetype: string; // File type
  presignedUrl?: string; // File preview/download URL
  width?: number; // Image width
  height?: number; // Image height
}[]
Example: 
// Write value
[
  {
    name: "document.pdf",
    type: "application/pdf",
    token: "abc123",
    size: 1024000
  }
]

// Return value
[
  {
    id: "att123",
    name: "document.pdf",
    path: "/uploads/document.pdf",
    token: "abc123",
    size: 1024000,
    mimetype: "application/pdf",
    presignedUrl: "https://app.teable.io/preview/document.pdf",
  },
  {
    id: "att456",
    name: "image.jpg",
    path: "/uploads/image.jpg",
    token: "def456",
    size: 2048000,
    mimetype: "image/jpeg",
    presignedUrl: "https://app.teable.io/preview/image.jpg",
    width: 1920,
    height: 1080
  }
]

​
9. Date Field

  • type: date
  • Write type: string (ISO 8601 format)
  • Return type:
    • isMultipleCellValue: false: string (ISO 8601 format)
    • isMultipleCellValue: true: string[] (ISO 8601 format) You can use new Date().toISOString() to get the ISO 8601 time format
Example: 
// Write value
"2024-09-02T02:51:03.875Z"

// Return value (isMultipleCellValue: false)
"2024-09-02T02:51:03.875Z"

// Return value (isMultipleCellValue: true)
["2024-09-02T02:51:03.875Z", "2024-09-02T02:51:03.875Z"]

​
10. Created Time Field

  • type: createdTime
  • Write type: Cannot be written directly
  • Return type:
    • isMultipleCellValue: false: string (ISO 8601 format)
    • isMultipleCellValue: true: string[] (ISO 8601 format)
Example: 
// Return value (isMultipleCellValue: false)
"2024-09-02T02:51:03.875Z"

// Return value (isMultipleCellValue: true)
["2024-09-02T02:51:03.875Z", "2024-09-02T02:51:03.875Z"]

​
11. Last Modified Time Field

  • type: lastModifiedTime
  • Write type: Cannot be written directly
  • Return type:
    • isMultipleCellValue: false: string (ISO 8601 format)
    • isMultipleCellValue: true: string[] (ISO 8601 format)
Example: 
// Return value (isMultipleCellValue: false)
"2023-04-15T10:30:00Z"

// Return value (isMultipleCellValue: true)
["2023-04-15T10:30:00Z", "2023-04-16T14:45:00Z"]

​
12. Checkbox Field

  • type: checkbox
  • Write type: boolean
  • Return type:
    • isMultipleCellValue: false: boolean
    • isMultipleCellValue: true: boolean[]
Example: 
// Write value
true

// Return value (isMultipleCellValue: false)
true

// Return value (isMultipleCellValue: true)
[true, false, true]

​
13. Rollup Field

  • type: rollup
  • Write type: Cannot be written directly
  • Return type: Depends on rollup configuration, can be number | string or their array forms
Example: 
// Return value (isMultipleCellValue: false)
42 // or "Summary Result"

// Return value (isMultipleCellValue: true)
[42, 17, 99] // or ["Summary 1", "Summary 2"]

​
14. Rating Field

  • type: rating
  • Write type: number
  • Return type:
    • isMultipleCellValue: false: number
    • isMultipleCellValue: true: number[]
Example: 
// Write value
4

// Return value (isMultipleCellValue: false)
4

// Return value (isMultipleCellValue: true)
[4, 3, 5]

​
15. Auto Number Field

  • type: autoNumber
  • Write type: Cannot be written directly
  • Return type:
    • isMultipleCellValue: false: number
    • isMultipleCellValue: true: number[]
Example: 
// Return value (isMultipleCellValue: false)
42

// Return value (isMultipleCellValue: true)
[42, 43, 44]

​
16. User Field

  • type: user
  • Write type:
    • isMultipleCellValue: false: { id: string, title: string }
    • isMultipleCellValue: true: { id: string, title: string }[]
  • Return type:
    • isMultipleCellValue: false: { id: string, title: string, email?: string, avatar?: string }
    • isMultipleCellValue: true: { id: string, title: string, email?: string, avatar?: string }[]
Example: 
// Write value (isMultipleCellValue: false)
{ id: "user123", title: "John Doe" }

// Write value (isMultipleCellValue: true)
[
  { id: "user123", title: "John Doe" },
  { id: "user456", title: "Jane Smith" }
]

// Return value (isMultipleCellValue: false)
{
  id: "user123",
  title: "John Doe",
  email: "john@example.com",
  avatar: "https://example.com/avatar.jpg"
}

// Return value (isMultipleCellValue: true)
[
  {
    id: "user123",
    title: "John Doe",
    email: "john@example.com",
    avatar: "https://example.com/avatar1.jpg"
  },
  {
    id: "user456",
    title: "Jane Smith",
    email: "jane@example.com",
    avatar: "https://example.com/avatar2.jpg"
  }
]

​
17. Created By Field

  • Write type: Cannot be written directly
  • Return type:
    • isMultipleCellValue: false: { id: string, title: string, email?: string, avatar?: string }
    • isMultipleCellValue: true: { id: string, title: string, email?: string, avatar?: string }[] Example:
// Return value (isMultipleCellValue: false)
{
  id: "user123",
  title: "John Doe",
  email: "john@example.com",
  avatar: "https://example.com/avatar.jpg"
}

// Return value (isMultipleCellValue: true)
[
  {
    id: "user123",
    title: "John Doe",
    email: "john@example.com",
    avatar: "https://example.com/avatar1.jpg"
  },
  {
    id: "user456",
    title: "Jane Smith",
    email: "jane@example.com",
    avatar: "https://example.com/avatar2.jpg"
  }
]

​
18. Last Modified By Field

  • Write type: Cannot be written directly
  • Return type:
    • isMultipleCellValue: false: { id: string, title: string, email?: string, avatar?: string }
    • isMultipleCellValue: true: { id: string, title: string, email?: string, avatar?: string }[]
Example: 
// Return value (isMultipleCellValue: false)
{
  id: "user123",
  title: "John Doe",
  email: "john@example.com",
  avatar: "https://example.com/avatar.jpg"
}

// Return value (isMultipleCellValue: true)
[
  {
    id: "user123",
    title: "John Doe",
    email: "john@example.com",
    avatar: "https://example.com/avatar1.jpg"
  },
  {
    id: "user456",
    title: "Jane Smith",
    email: "jane@example.com",
    avatar: "https://example.com/avatar2.jpg"
  }
]